Experimental Study On Analytical Method Of Stability Of Granular Mixtures Slope

Distributed regionally in some areas of the southwest and northwest in China, granular mixtures slope, also known as sand-sliding slope, is usually composed of crushed stone, gravel and sand. With a loose structure, it almost contains no fine particles which can be connected with other cements, thus always being in a state of "loose sand". With great sensitivity to external disturbances, granular mixtures slope is usually very active, causing harm to the safe running of linear transport along the route. What’s more, granular mixtures are always deformed and destructed suddenly, so they posed a serious threat to personal and property safety. The study of granular mixtures slope deformation and destruction was started late, and previous studies were mainly focused on nonlinear dynamics of accumulated granular mixtures. Through sand-pile experiment, one-sided-slope test and other physical experiments, granular mixtures slope was considered as a typical dissipative dynamic system of diversified extensive space degree of freedom and it conformed to the principle of self-organized criticality. The instability of a place on the slope could be spread to other nearby area, resulting in the instability of a large area of granular mixtures material, thus self-organized criticality of granular mixtures would be affected by scale and gradation. Due to the self-organized criticality, granular mixtures slope in critical state, if disturbed, would cause unpredictable destruction. This paper suggests that there is not only movement of single particle or multiple particles but alsooverall instability of large area on granular mixtures slope.On the basis of substantive granular mixtures related documentation at home and abroadand a lot of first-hand information, this paper mainly studies it from the perspective of geological disaster by making use of theory derivation and physical simulation experiments. The main contents include:(1) This paper analyzes the distribution characteristics, material composition, formation conditions and influencing factorsof granular mixtures slope by means of field investigation, sampling and screening.(2) This paper analyzes the contacteffects of granular particles, finds out shear strength characteristics of the particles by direct shear test, and shows the influence of particle size and gradation on shear strength.(3) This paper clarifiesthe destruction caused by particles movement on the slope surface by dividing granular mixtures slope activity stages, analyzes the single particle starting mechanics criterion on the slope surface and verifiesthe practicability of it by the experimental method. The conclusion fitsvery well with experimental data: the starting of a single regularly-shaped particle on the slope surface is independent of the weight of the particle itself, as long as the geometric feature meet particles requirement; the shape of particle has a large influence on particle starting conditions.(4) Through physical simulation of overall deformation and destruction mechanism, this paper proposes five kinds of granular mixtures slope deformation and destruction modeswhich are particles slip flow on the slope surface, creep shearing damage on the slope surface, the traction-bulging destruction, retrogressive destruction and collapsing destruction.(5) This paper carries out a further study on the stability assessment of granular mixtures slope and, combining with physical simulation experiments, puts forward different targeted stability assessment methods for different failure modes. As for particles slip flow on the slope surface, key particles distinguishing method is proposed; as for overall creep slip shearing failure mode, the traditional Bishop slices method recommended.